[jvm-packages] Upgrade Scala to 2.11.12 to address CVE-2017-15288 (#3816)
[jvm-packages] Upgrade Scala to 2.11.12 to address CVE-2017-15288 (#3816)

A privilege escalation vulnerability (CVE-2017-15288) has been
identified in the Scala compilation daemon. See
https://nvd.nist.gov/vuln/detail/CVE-2017-15288

Fix: Upgrade Scala to 2.11.12.
dmlc/xgboost,dmlc/xgboost,dmlc/xgboost,dmlc/xgboost,dmlc/xgboost,dmlc/xgboost